<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
<script>
    //求n-m之间所有数的和
    // function everySum (n,m){
    //     var sum =0;
    //     for (var i =n;i<=m;i++){
    //         sum+=i;
    //     }
    //     return sum;
    // }
    // var num1=parseInt(prompt("请输入第一个数字"));
    // var num2=parseInt(prompt("请输入第二个数字"));
    // console.log(everySum(num1,num2));
    //求圆的面积
    function getRadius(r) {
        return Math.PI * r * r;
    }

    console.log(getRadius(5));


</script>
</body>
</html>
